This is Raven, the University of Cambridge's central web authentication service. Web-based services use Raven when they need to to know who in the University is using them.
The Computing Service's Raven documentation contains more information about Raven (including information on how to get a Raven password, other related information, and a test page you can use to check that your Raven account is working). Requests for support on Raven should be addressed to the UCS Service Desk.
Always log out after using a Raven-authenticated site, to prevent others from accessing your personal information and visiting web sites using your identity. The best way of doing this is to completely exit your browser.
If for any reason you can't exit your browser you should first log-out of all personalised sites that you have accessed and then explicitly logout from Raven.
Changing your password
You can change your password and manage your Raven account from the account management page. Your initial password is deliberately difficult to remember so it's a good idea to change it to something that only you know as soon as possible.
You will be automatically offered the opportunity to log-in to Raven when necessary. If you really want to, you can explicitly login to Raven.
You can check your current login status.
Information for webmasters
Information about using Raven to protect web servers and web applications, along with software to help you to do so, can be found on the Raven project pages.